Variations In CO2 Concentration Research Articles

Influence of Freezing and Storage Procedure on Human Urine Samples in NMR-Based Metabolomics.

It is consensus in the metabolomics community that standardized protocols should be followed for sample handling, storage and analysis, as it is of utmost importance to maintain constant measurement conditions to identify subtle biological differences. The aim of this work, therefore, was to systematically investigate the influence of freezing procedures and storage temperatures and their effect on NMR spectra as a potentially disturbing aspect for NMR-based metabolomics studies. Urine samples were collected from two healthy volunteers, centrifuged and divided into aliquots. Urine aliquots were frozen either at −20 °C, on dry ice, at −80 °C or in liquid nitrogen and then stored at −20 °C, −80 °C or in liquid nitrogen vapor phase for 1–5 weeks before NMR analysis. Results show spectral changes depending on the freezing procedure, with samples frozen on dry ice showing the largest deviations. The effect was found to be based on pH differences, which were caused by variations in CO2 concentrations introduced by the freezing procedure. Thus, we recommend that urine samples should be frozen at −20 °C and transferred to lower storage temperatures within one week and that freezing procedures should be part of the publication protocol.

Variability of CO2 concentrations and fluxes in and above an urban street canyon

The variability of CO2 concentrations and fluxes in dense urban environments is high due to the inherent heterogeneity of these complex areas and their spatio-temporally variable anthropogenic sources. With a focus on micro- to local-scale CO2-exchange processes, measurements were conducted in a street canyon in the city of Basel, Switzerland in 2010. CO2 fluxes were sampled at the top of the canyon (19 m) and at 39 m while vertical CO2 concentration profiles were measured in the center and at a wall of the canyon. CO2 concentration distributions in the street canyon and exchange processes with the layers above show, apart from expected general diurnal patterns due mixing layer heights, a strong dependence on wind direction relative to the canyon. As a consequence of the resulting corkscrew-like canyon vortex, accumulation of CO2 inside the canyon is modulated with distinct distribution patterns. The evaluation of diurnal traffic data provides good explanations for the vertical and horizontal differences in CO2-distribution inside the canyon. Diurnal flux characteristics at the top of the canyon can almost solely be explained with traffic density expressed by the strong linear dependence. Even the diurnal course of the flux at 39 m shows a remarkable relationship to traffic density for east wind conditions while, for west wind situations, a change toward source areas with lower emissions leads to a reduced flux.

Geodynamic processes in the NW Bohemian swarm earthquake region, Czech Republic, identified by continuous gas monitoring

AbstractThe time series of two continuously operating gas monitoring stations at Oldřišská and Nový Kostel located along seismoactive faults in the epicentral area of the NW Bohemian swarm earthquakes (Czech Republic) are compared with water level fluctuations in two boreholes positioned along these faults and with gas flux variations of a mofette at the Soos mofette field at 9 km distance. The seasonal trend of the monitored CO2 concentration with a maximum in November and a minimum in March/April is governed by groundwater temperatures, superimposed in spring by soil temperatures. CO2 concentration variations identified at Oldřišská are also reflected in gas flux variations in the Soos mofette and/or water level fluctuations of two boreholes. Variations in the gas monitoring recordings of station at Nový Kostel are also linked with variations at Oldřišská. In all data sets, diurnal variations generated by earth tides occur, reflecting a daily stress – fault permeability cycle. Additional stress interferes with this cycle. Significant, abrupt changes are attributed to geodynamic processes linked with seismic events, as revealed by local seismicity or by the transient of waves of a strong remote earthquake. Simultaneous variations of the gas concentrations in the Nový Kostel area and in the gas flux in the Soos point to an interconnected hydraulic conductive fault systems present in the northern part of the Cheb Basin. Sharp falls in gas concentration, during or subsequent to, earthquake swarms may reflect fault compression associated with impeded gas migration. However, gas variations also occur in periods without seismic activity, indicating changes in fault permeability were caused by local aseismic fault movements, as revealed by events with opposite trends in the gas recordings at Oldřišská, Nový Kostel and the Soos. Therefore, a mathematical approach to establish a correlation between seismicity and gas geochemical variations is not possible.

通気性撥水チューブを用いた水中二酸化炭素濃度の計測手法の有効性検証

A carbon dioxide meter with water-resistant breathable tube was developed in order to measure CO2 concentration in water. Laboratory experiments were conducted for verification of the effectiveness of this method. After measuring the time variations of CO2 concentration in water aerating by air pump or adding carbonic water, it was confirmed that this method was useful to evaluate the carbon cycle in coastal zone. Furthermore, the CO2 production from sediment by decomposition of organic matter was confirmed by measuring the time variations of CO2 and DO concentrations in the water above sediment at the same time.

The Chamber for Studying Rice Response to Elevated Nighttime Temperature in Field

An in situ temperature-controlled field chamber was developed for studying a large population of rice plant under different nighttime temperature treatments while maintaining conditions similar to those in the field during daytime. The system consists of a pipe hoop shed-type chamber with manually removable covers manipulated to provide a natural environment at daytime and a relatively stable and accurate temperature at night. Average air temperatures of 22.4 ± 0.3°C at setting of 22°C, 27.6 ± 0.4°C at 27°C, and 23.8 ± 0.7°C ambient conditions were maintained with the system. No significant horizontal and vertical differences in temperature were found and only slight changes in water temperatures were observed between the chambers and ambient conditions at 36 days after transplanting. A slight variation in CO2 concentration was observed at the end of the treatment during the day, but the 10-μmol CO2 mol−1 difference was too small to alter plant response. The present utilitarian system, which only utilizes an air conditioner/heater, is suitable for studying the effect of nighttime temperature on plant physiological responses with minimal perturbation of other environmental factors. At the same time, it will enable in situ screening of many rice genotypes.

Investigation on the interannual variability of carbon dioxide column-averaged mole fractions in Peninsular Malaysia: 2003-2009

Carbon dioxide (CO2) is the most important anthropogenic greenhouse gas contributing to global climate change. The aim of this study was to assess the seasonal variations of CO2 concentrations in Peninsular Malaysia from January 2003 to December 2009 using level 3 of the CO2 column WFMD version 2.1 retrieved from SCIAMACHY satellite. The analysis for five locations showed that CO2 increased by approximately 15 ppm from 2003 to 2009. As the northeastern monsoon prevails, cold air outbreaks from Siberia are high and spread to the equatorial region in the form of northeasterly cold surge winds around the low-level anticyclones over South East Asia. Inversely, the air masses from southwesterly contribute to long range air pollution, including CO2 due to transportation of pollutants by wind during southwestern monsoon associated with biomass burning in Sumatra, Indonesia.

Analysis of the carbon dioxide concentration in the lowest atmospheric layers and the factors affecting China based on satellite observations

Carbon dioxide (CO2) is the most important anthropogenic greenhouse gas contributing to global climate change. SCIAMACHY on board ENVISAT (launched in 2002) is the first satellite instrument to monitor the changes in CO2 concentration in the lowest atmospheric layers. The temporal and spatial distribution of CO2 (2003–2009) concentration based on SCIAMACHY over China is presented and discussed. It shows an annual increase and a seasonal cycle. The CO2 annual growth rate was about 1.8 ppm year−1, with the highest value being in spring and the lowest in autumn. The CO2 concentration variation is determined by many complex factors. In this article, we analyse the important factors affecting CO2 variations, with special emphasis on terrestrial ecosystems and energy consumption. Terrestrial ecosystems are an important sink in the global carbon cycle. The relationship between CO2 concentration and Moderate Resolution Imaging Spectroradiometer (MODIS) net primary production (NPP) in 2008 is analysed. CO2 concentration is inversely proportional to NPP both in regions with high-density vegetation and in deserts. The Yunnan province has the highest NPP value and the lowest CO2 concentration, whereas the Takla Makan Desert has the lowest NPP value and the highest CO2 concentration. Energy consumption is the main emission source of atmospheric CO2. CO2 emissions from energy consumption show a steady increase in China since 1980. China's CO2 concentration variation shows a high correlation with energy consumption (coefficient of determination (R 2) > 0.8). The regions with high energy consumption are major industrial regions such as Shandong, Guangdong, Jiangsu, Zhejiang, Hebei, and Henan.

The sources and sinks of CO2 in caves under mixed woodland and grassland vegetation

We measured concentrations and stable carbon isotope compositions of carbon dioxide in the atmospheres of three caves in central Texas and one cave in southern Arizona in order to identify CO2 sources and sinks. The vegetation above the caves studied is either savannah (two caves, above which vegetation has been minimally disturbed) or discrete patches of grassland and woodland (two caves, above which vegetation has been highly disturbed). We tested two hypotheses concerning CO2 in the cave atmospheres: (1) cave ventilation by tropospheric air is the primary sink for CO2 and (2) CO2 is primarily derived from the deepest rooting plants growing above the caves. Within caves, we monitored CO2 at individual locations on monthly and daily time-scales and measured CO2 along transects with increasing distance from the cave entrances. We also measured CO2 in the pore spaces of soils under grasses and trees above each of the caves. We calculated δ13C values of respired CO2 (δ13Cr) for all gas samples using measured δ13C values and CO2 concentrations. We then identified the sources of cave CO2 by comparing cave-air and soil CO2δ13Cr values. At all locations in each Texas cave, CO2 concentrations were highest (lowest) and δ13C values were lowest (highest) during the summer (winter). Cave-air CO2 concentrations consistently increased and δ13C values consistently decreased with distance from the cave entrances. Similar but smaller magnitude seasonal variations in CO2 concentrations occurred in the Arizona cave and no seasonal or spatial variation in the δ13C of cave-air CO2 was observed. The mean δ13Cr values of CO2 in soils under grass were 3.5–4.5‰ higher than the δ13Cr values of CO2 in soils under trees. In the caves under savannah, mean δ13Cr values of cave-air CO2 (−24‰ in both caves) were within 1‰ of the mean δ13Cr values of CO2 in soils under trees. In caves covered by large, contiguous areas of grassland, the δ13Cr values of cave-air CO2 were similar to grassland soil values during the summer and were intermediate between grassland and woodland soil values during the winter. The observed spatial and temporal variations in cave-air CO2 are consistent with density-driven ventilation controlled by seasonal surface temperature changes as the primary sink for CO2 in the Texas caves. The consistent agreement between soil and cave δ13Cr values indicate that the same mixing and diffusion equations that are used to calculate δ13Cr values of soil CO2 also apply to cave-air CO2. Our results suggest that the majority of CO2 advects or diffuses into these caves from soils as a gas rather than being transported in aqueous solution. Measured δ13Cr values and numerical production-diffusion modeling supports our hypothesis that the majority of gaseous CO2 in these caves is derived from deeply rooted vegetation. The carbon isotope composition of groundwater and speleothem calcite used for paleoclimate records are therefore likely biased toward deeply rooted plants, even if sparsely present.

Rain Induced Changes in Carbon Dioxide Concentrations in the Soil–Lake–Brook Continuum of a Boreal Forested Catchment

The numerous water bodies and their riparian zones in the boreal zone are crucial to lateral carbon transport and can thus be very significant for carbon cycle on the landscape level. Therefore, we installed automatic measurement systems with Vaisala CARBOCAP CO2 probes (Vaisala Oyj, Vantaa, Finland) in the riparian zone soil matrix around a small headwater lake, in the lake itself, and in the outflowing brook and followed the seasonal and diurnal variation in CO2 concentration as well as rain event‐driven changes in this natural‐state soil–lake–brook continuum in Southern Finland. Seasonal variation was greatest and concentrations highest deep in the soil and in the lake, but were also noticeable in the brook. On the other hand, diurnal variation was highest in shallow soil layers and the lake surface. In the brook, the influence of the riparian zone superseded that of the lake at less than 150 m distance, which resulted in wider variation and higher concentrations of CO2. After the rain event, the normal diurnal pattern was changed, and the CO2 concentration in the soil increased as water filled the soil pores and slowed down the diffusion. Even though the water with lower CO2 concentration from the lake diluted the CO2 concentration in the brook, the input from the soil dominated the flow after the rain and concentrations increased. On an annual basis, the flow of terrestrial dissolved inorganic carbon (DIC) into the aquatic ecosystem was 1–13% of terrestrial net ecosystem production (NEP).

Three-dimensional variations of atmospheric CO<sub>2</sub>: aircraft measurements and multi-transport model simulations

Abstract. Numerical simulation and validation of three-dimensional structure of atmospheric carbon dioxide (CO2) is necessary for quantification of transport model uncertainty and its role on surface flux estimation by inverse modeling. Simulations of atmospheric CO2 were performed using four transport models and two sets of surface fluxes compared with an aircraft measurement dataset of Comprehensive Observation Network for Trace gases by AIrLiner (CONTRAIL), covering various latitudes, longitudes, and heights. Under this transport model intercomparison project, spatiotemporal variations of CO2 concentration for 2006–2007 were analyzed with a three-dimensional perspective. Results show that the models reasonably simulated vertical profiles and seasonal variations not only over northern latitude areas but also over the tropics and southern latitudes. From CONTRAIL measurements and model simulations, intrusion of northern CO2 in to the Southern Hemisphere, through the upper troposphere, was confirmed. Furthermore, models well simulated the vertical propagation of seasonal variation in the northern free troposphere. However, significant model-observation discrepancies were found in Asian regions, which are attributable to uncertainty of the surface CO2 flux data. In summer season, differences in latitudinal gradients by the fluxes are comparable to or greater than model-model differences even in the free troposphere. This result suggests that active summer vertical transport sufficiently ventilates flux signals up to the free troposphere and the models could use those for inferring surface CO2 fluxes.

Seasonal and spatial variability of CO2emission from a large floodplain lake in the lower Amazon

[1] The inundation status of the Amazon floodplain affects biogenic gas production and evasion. We analyzed spatial variability of dissolved CO2 concentration and gas evasion in a large floodplain lake in the lower reach of the Amazon River in four hydrological phases. We calculated surficial CO2 concentrations from measurements of pH, dissolved inorganic carbon, temperature, and conductivity and used meteorological data to calculate gas transfer coefficients to estimate CO2 evasion. Gas transfer coefficients that take into account both wind and heating and cooling at the lake's surface are on the order of 10 cm hr−1, approximately four times higher than values previously used in regional estimates of gas evasion from lakes on the Amazon floodplain. Supersaturation of CO2 occurred throughout the lake and was higher in the littoral zone and in regions receiving Amazon River inflows. CO2 concentration was reduced in regions with phytoplankton blooms. The range of CO2 concentrations was least at low water, 47 μM to 233 μM, and largest at high water, 1 μM to 656 μM; the average annual value was 125 μM. We estimate mean (±standard deviation) fluxes from open-water in L. Curuai to the atmosphere of 44 ± 15, 348 ± 13, 371 ± 23, and 364 ± 20 mmol CO2 m−2 d−1 during receding, low, rising, and high water, respectively. The error associated with these values reflects, for each hydrological phase, the spatial variation in CO2 concentration in L. Curuai, a likely range in atmospheric CO2 levels and temporal variations in gas transfer coefficient within 10-day periods.

Variation of H2O, CO2, and CO2 isotope composition in tree rings of Siberian stone pine

The experimental measurements of H2O, CO2, and the carbon isotope content of CO2, vacuum-desorbed from tree rings of the Siberian stone pine disc, have been obtained. It is shown that: 1) certain cyclicity exists in annual trends of H2O and CO2; 2) the amplitude of CO2 cycles has markedly risen after 1960; 3) the annual trend of the CO2 concentration in the rings correlates with an increase in atmospheric CO2 concentration; 4) the carbon isotope content varies with the variation of CO2 concentration in a sample.

Experimental study on variations of CO2 concentration in the presence of indoor plants and respiration of experimental animals

This study aims to suggest an improved experimental method to reveal the ability of indoor plants to reduce CO2 concentrations, as well as to display the individual CO2 reduction characteristics of various indoor plants in accordance with this improved method. In previous studies, experiments were conducted under the condition in which the CO2 concentration in the experimental chamber is set only once to a high initial level of 1,000 ppm. However, in real conditions, CO2 concentration gradually increases in a room after the occupants enter. Hence, the existing experimental method can be improved in view of “light saturation and CO2 compensation”. Accordingly, in this study, the CO2 reduction characteristics of indoor plants under 2 conditions used in the existing method of measurement (Case 1) and the condition in the new method, which considers that CO2 concentration gradually increases through the respiration of experimental animals (Case 2)-were measured and compared against each other. For all plant samples, the level of CO2 reduction was higher in Case 2 than in Case 1, and the rate of CO2 reduction increases with time. The inflection point of CO2 concentration appeared at leaf areas of 9,000 cm2 in peace lily and areca palm, and 6,000 cm2 in weeping fig.

Simulation of variability in atmospheric carbon dioxide using a global coupled Eulerian – Lagrangian transport model

Abstract. This study assesses the advantages of using a coupled atmospheric-tracer transport model, comprising a global Eulerian model and a global Lagrangian particle dispersion model, to improve the reproducibility of tracer-gas variations affected by the near-field surface emissions and transport around observation sites. The ability to resolve variability in atmospheric composition on an hourly time-scale and a spatial scale of several kilometers would be beneficial for analyzing data from continuous ground-based monitoring and from upcoming space-based observations. The coupled model yields an increase in the horizontal resolution of transport and fluxes, and has been tested in regional-scale studies of atmospheric chemistry. By applying the Lagrangian component to the global domain, we extend this approach to the global scale, thereby enabling computationally efficient global inverse modeling and data assimilation. To validate the coupled model, we compare model-simulated CO2 concentrations with continuous observations at three sites: two operated by the National Oceanic and Atmospheric Administration, USA, and one operated by the National Institute for Environmental Studies, Japan. As the goal of this study is limited to introducing the new modeling approach, we selected a transport simulation at these three sites to demonstrate how the model may perform at various geographical areas. The coupled model provides improved agreement between modeled and observed CO2 concentrations in comparison to the Eulerian model. In an area where variability in CO2 concentration is dominated by a fossil fuel signal, the correlation coefficient between modeled and observed concentrations increases by between 0.05 to 0.1 from the original values of 0.5–0.6 achieved with the Eulerian model.

Analysis of spatial and temporal variations of carbon dioxide over China using SCIAMACHY satellite observations during 2003–2005

This study aims to assess CO2 levels in China, based on the dry air column-averaged mixing ratios of CO2 measured by the Scanning Imaging Absorption spectrometer for Atmospheric CartograpHY (SCIAMACHY) instrument on board ENVISAT and emission inventories. A land cover and statistical data set, the Regional emission inventory in Asia (REAS), was also used in this study. The results show that the spatial variations of the CO2 concentration in the whole of China are obvious, and with clear seasonal fluctuation during 2003–2005. The monthly averaged variability of CO2 over China fluctuates, with the peak occurring in April to May and the trough occurring in August to October. The largest peak-to-trough amplitude was about 16 ppm in this period. The spatial and temporal variations of CO2 had a strong correlation with anthropogenic CO2 emissions and regional terrestrial ecosystem, as well as local meteorological conditions. This paper illustrates that satellite data are promising for obtaining a comprehensive understanding of the variations of atmospheric CO2 concentrations and of CO2 emissions to the atmosphere.

Crassulacean acid metabolism in the context of other carbon-concentrating mechanisms in freshwater plants: a review

Inorganic carbon can be in short supply in freshwater relative to that needed by freshwater plants for photosynthesis because of a large external transport limitation coupled with frequent depleted concentrations of CO(2) and elevated concentrations of O(2). Freshwater plants have evolved a host of avoidance, exploitation and amelioration strategies to cope with the low and variable supply of inorganic carbon in water. Avoidance strategies rely on the spatial variation in CO(2) concentrations within and among lakes. Exploitation strategies involve anatomical and morphological features that take advantage of sources of CO(2) outside of the water column such as the atmosphere or sediment. Amelioration strategies involve carbon-concentrating mechanisms based on uptake of bicarbonate, which is widespread, C(4)-fixation, which is infrequent, and crassulacean acid metabolism (CAM), which is of intermediate frequency. CAM enables aquatic plants to take up inorganic carbon in the night. Furthermore, daytime inorganic carbon uptake is generally not inhibited and therefore CAM is considered to be a carbon-conserving mechanism. CAM in aquatic plants is a plastic mechanism regulated by environmental variables and is generally downregulated when inorganic carbon does not limit photosynthesis. CAM is regulated in the long term (acclimation during growth), but is also affected by environmental conditions in the short term (response on a daily basis). In aquatic plants, CAM appears to be an ecologically important mechanism for increasing inorganic carbon uptake, because the in situ contribution from CAM to the C-budget generally is high (18-55%).

Dynamic changes of canopy‐scale mesophyll conductance to CO2 diffusion of sunflower as affected by CO2 concentration and abscisic acid

Leaf-level measurements have shown that mesophyll conductance (g(m)) can vary rapidly in response to CO₂ and other environmental factors, but similar studies at the canopy-scale are missing. Here, we report the effect of short-term variation of CO₂ concentration on canopy-scale g(m) and other CO₂ exchange parameters of sunflower (Helianthus annuus L.) stands in the presence and absence of abscisic acid (ABA) in their nutrient solution. g(m) was estimated from gas exchange and on-line carbon isotope discrimination (Δ(obs)) in a ¹³CO₂/¹²CO₂) gas exchange mesocosm. The isotopic contribution of (photo)respiration to stand-scale Δ(obs) was determined with the experimental approach of Tcherkez et al. Without ABA, short-term exposures to different CO₂ concentrations (C(a) 100 to 900 µmol mol⁻¹) had little effect on canopy-scale g(m) . But, addition of ABA strongly altered the CO₂-response: g(m) was high (approx. 0.5 mol CO₂ m⁻² s⁻¹) at C(a) <200 µmol mol⁻¹ and decreased to <0.1 mol CO₂ m⁻² s⁻¹ at C(a) >400 µmol mol⁻¹. In the absence of ABA, the contribution of (photo)respiration to stand-scale Δ(obs) was high at low C(a) (7.2 ‰) and decreased to <2 ‰ at C(a) > 400 µmol mol⁻¹. Treatment with ABA halved this effect at all C(a) .

Thermal analysis scheme aimed at better understanding of the Earth’s climate changes due to the alternating irradiation

Methodological scheme of thermal analysis is used for portraying the Earth environmental research and climate changes showing particularly the history, effect of atmosphere reflection (albedo) and absorption (so called greenhouse effect included). The net behavior of the Earth as a black body is reviewed. The most influential on climate changes is alteration of the geometry of the Earth trajectory and the irradiative power of the Sun (as a standard thermo-analytical pair of the sample and radiator). Thermodynamic basis of water vapor impacts is pointed out, the absorption spectra of atmosphere emphasized and temperature gradients indicated. The historical course of the Earth temperature and CO2 concentration is put in analogy with the method of gas desorption analysis, which supports the view that the variation of CO2 concentration recorded in the past may not be alone blamed for temperature changes.

Nano-size quartz accumulation in reservoir chalk, Ekofisk Formation, South Arne Field, North Sea

AbstractIn the oil fields in the Central Graben of the North Sea, Maastrichtian chalk is an important hydrocarbon reservoir, but oil may also be found in the Danian chalk, consisting of white chalk interbedded with clay layers. Within the chalk section, discrete intervals appear like chalk but contain large amounts of quartz (up to 100%). The aim of the present investigation is to reveal the mechanism for formation of the quartz in these intervals and to discuss their regional distribution and importance for the reservoir properties. Samples of chalk, including quartz-rich intervals, and clay layers from three wells SA-1, Rigs-1 and Rigs-2 in the South Arne Field have been investigated. Calcite-free residues obtained using a buffered dissolution of calcite were investigated using X-ray diffraction, scanning electron microscopy and atomic force microscopy. The main silica phase in the Upper Cretaceous–Danian chalk in the three wells is a nano-size α-quartz. This has probably formed from Si dissolved from radiolarians in the free-water phase. The 600 Å diameter α-quartz spheres precipitated in the free-water phase with subsequent flocculation of the spheres and sedimentation of the flocs. Variations in the proportion of quartz in the chalk are attributed to variations in the amount of radiolarians in combination with variations in CO2 concentrations in the water; increased CO2 causes dissolution of coccoliths and thus a relative enrichment in quartz. This formation mechanism is regional and makes it probable that the layers rich in nano-quartz may be found over large areas provided that the chalk is authigenic. Quartz-rich layers are generally of low permeability and in areas with authigenic chalk these layers may act as internal seals in chalk reservoirs.

Temporal and spatial variability of dissolved inorganic carbon in a boreal stream network: Concentrations and downstream fluxes

Carbon dioxide (CO2) and dissolved inorganic carbon (DIC) concentrations and export were analyzed throughout a 67 km2 boreal stream network in northern Sweden. 700 DIC and CO2 samples from 14 subcatchments were collected in 2006 and 2007. All sites were consistently supersaturated in CO2 with respect to the atmosphere. Temporal variability of DIC and CO2 concentration was best correlated with discharge, with concentrations generally diluting at high discharge. However, the variability in CO2 concentration was also dependent on the specific pH range of the stream, as variability was greatest in acidic headwater streams and lowest in larger circumneutral streams. In the larger ones the increase in the CO2 proportion of DIC at increased discharge counteracts the dilution of CO2. The shift toward proportionally more CO2 of the DIC at higher discharge is caused by decline in pH. Spatial patterns showed that DIC and CO2 concentrations were best correlated with peatland coverage of the subcatchment. The highest concentrations were found in headwater streams draining peatlands. The downstream export of DIC from the catchment outlet constitutes 19% of the total downstream export of carbon (DIC + DOC), or 0.7 (±0.09) g C m−2 yr−1. This study demonstrates the importance of including fluvial fluxes of inorganic carbon in landscape carbon budgets via runoff, and also highlights the need to account for stream evasion of CO2 to the atmosphere in such estimates since it can be larger than the downstream DIC export.